1. Field of the Invention
The present invention relates to a semiconductor device that is used by utilizing optical communications technology and to an optical signal input/output device using same, and more particularly to a semiconductor device that enables the processing of multiple optical signals and to an optical signal input/output device using same.
2. Background Art
In recent years, with the rapid proliferation of the Internet and the like, the capacity for information processing handled by transmission devices such as routers, servers, switches and the like, storage devices, and the like is increasing rapidly. Currently, boards with electrical wiring, electronic components mounted on such boards, and electrical transmission lines interconnecting the electronic components are packaged in such devices. In other words, most of the data that is inputted from outside the devices are processed as electrical signals within the devices. However, the amount and speed of information processing handled per device is growing year by year, and limits are occurring for the electrical interconnects within devices for the following reasons:                (1) high frequency noise occurs as speed increases. Device malfunctions increase due to this increase in noise;        (2) electrical loss in the electrical transmission lines on the board becomes greater at high frequencies, thereby placing a limit on how fast electrical signals can be made to be; and        (3) as electricity reaches high frequencies, crosstalk occurs among the electrical wiring, and malfunctions occur in devices.        
In recent years, in order to resolve the above-mentioned shortcomings of electrical interconnects, devices in which electronic components are interconnected with optical signals have started to become the subject of research and development. Since light is non-inductive, it has an advantage which is that noise, loss, and crosstalk do not occur even when the transmission speed of optical signals is increased. In a conventional optical signal input/output device in which information transmission between electronic components is carried out by means of optical signals, a surface-type optical device array is mounted on an LSI chip, and the surface-type optical device array and a multilayer optical waveguide portion on a printed board are optically coupled as disclosed in, for example, JP Patent Publication (Kokai) No. 2001-185752 A. Electrode pads on the printed board and an electrical wiring layer of the LSI chip are bonded by means of solder bumps, and through these solder bumps, power is supplied and control signals are sent from the printed board to the LSI chip and the surface-type optical devices. The exchange of signals using a TBGA (Tape Ball Grid Array) package structure is as follows. Input optical signals travel through a multilayer optical waveguide portion formed on a printed board, and are inputted to a surface-type optical device array having a light-receiving function. The inputted optical signals are converted into electrical signals by the surface-type optical device array, and are inputted to an LSI chip. Conversely, the electrical signals outputted by the LSI chip are converted into optical signals at surface-type optical devices having a light emitting function, and are then inputted to the multilayer optical waveguide portion. In general, it is difficult to form vias and through-holes for electrical conduction in a multilayer optical waveguide portion. Therefore, it has been conventional to provide electrode pads on a printed board and to not form multilayer optical waveguides on the upper surface of the electrode pads.    [Patent Document 1] JP Patent Publication (Kokai) No. 2001-185752 A